In the past 2 months I have had an issue with my 7D which is almost 2 years old and only shot 1948 times. The shutter when pressed half way to check the exposure details, fires 2 shots. This has happened only 3 times, the first 2 were in ISO 100 1/50 sec in Av mode and the third set at ISO 6400 trying to get a shot of the full moon last night.
The camera is set for RAW (of course) and ONE SHOT.

One Shot is the AF mode (that focuses once and doesn't attempt to track)

Single shooting is the drive mode that only takes one shot. (page 93 in the manual)

High-speed continuous shooting is the 8 fps mode in which you only need to press the shutter release down for 1/8' to get two shots.

Maybe the new firmware upgrade in August will fix the problem but I was wondering if anyone else has had this experience.
Thanks for any input